This invention relates to a portable system for analyzing human gait. More particularly, this invention relates to foot mounted sensors comprising a detachable plantar pressure collection unit, a detachable motion tracking unit, a detachable processing and display unit, a detachable sole unit, a soft foot casing unit, and a shank cover.
U.S. Pat. No. 5,899,963 entitled: System and Method for Measuring Movement of Objects, discloses a device that measures the distance traveled, speed and height jumped while a person is running or walking. An electronic circuit performs mathematical calculations to determine distance and height. A microprocessor calculates an output speed based upon step-distance and elasped time, and the distance traveled from the sum of all previous steps. A display shows the distance traveled, speed or height jumped.
U.S. Pat. No. 5,875,571 entitled: Insole Pad having a Step-Counting Device, includes an insole pad body, a fluid bag, a connecting portion, a pressure-sensitive sensor, a thermostat, a transmitting circuit, and a receiving circuit. Variation in pressure and temperature signals are detected, and converted to values, which are transmitted by an RF signal, and displayed on a liquid crystal display.
U.S. Pat. No. 4,745,930 entitled Force Sensing Insole for an Electro-Goniometer, is used for analyzing the gait of a patient. The insole comprises three separate chambers, which each contain contact switches. A plurality of parallel fingers are provided on the inwardly facing surface of the chambers, and extend to a terminal at the end of the strip.
U.S. Pat. No. 3,974,491, entitled: Load Signaling Device for a Patient""s Foot, discloses a foot pad sized to substantially cover the inner sole of a shoe. A resilient liquid filled tube is positioned within the foot pad. A pressure responsive means in communication with the liquid actuates a signal means at a predetermined pressure of said liquid.
U.S. Pat. No. 3,791,375, entitled: Device for Sensing and Warning of Excessive Ambulation Force, discloses a fluid containing load cell which deflects and changes its volume in accordance with the amount of load thereon. An alarm indicates when a predetermined load on the cell is reached.
U.S. Pat. No. 4,647,918, entitled: Multi-event Notification System for Monitoring Critical Pressure Points on Persons with Diminished Sensation of the Feet, discloses a plurality of pressure transducers for measuring and monitoring pressure, are connected to a microprocessor, which is programmable to monitor pressure over a pre-selected time interval. An alarm indicator is actuated when the total number of pressure events exceed the threshold limit.
U.S. Pat. No. 4,703,445, entitled: Atheletic Shoe for Running Disciplines and a Process for Providing Information and/or for Exchanging Information Concerning Moving Sequences in Running Disciplines, discloses a process for gathering information comprising at least one sensor located in the sole, to emit at least one output signal which is transmitted to a remote receiver linked to a computer. The computer determines the distance between the first and second shoes, based upon the delay of the emissions, as well as other characteristic values related to stride rate and length of stride.
U.S. Pat. No. 5,929,332, entitled: Sensor Shoe for Monitoring the Condition of a Foot, discloses a sensor shoe having a base, a foot receiving portion extending from the base, and an inner sole positioned within the foot receiving portion and atop the base. Sensors in the inner sole generate signals to determine if a critical situation exists. A microcomputer releases medication when a critical situation exists.
U.S. Pat. No. 5,583,776, entitled: Dead Reckoning Navigational System using Accelerometer to Measure Foot Impacts, integrates GPS data, dead reckoning sensors, and digital maps into a low cost, self-contained navigation instrument having a built-in radio frequency transponder, enabling individual positions to be monitored by a central coordinating facility.
U.S. Pat. No. 5,485,402, entitled: Gait Activity Monitor, to determine and record the number of steps taken by a wearer during selected intervals. An optical transmitter receive permits the monitor to be optically coupled to a computer for transmitting data. The duration of the selected time interval can be changed, and the gait activity data stored and downloaded for analyzing the data and for generating selected reports.
U.S. Pat. No. 6,010,465, entitled: Apparatus and Method for Characterizing Gait, discloses a treadmill having multiple transducers to identify the occurrence of heel-strike and toe-off movements while walking or running. A computer identifies two non-contiguous groups of transducers measuring a force greater than zero, and calculates the forces exerted by each foot.
Also noted of interest is an article by Jacqueline Wertsch, MD, John Webster PhD, and Willis Tompkins PhD, published in the Journal of Rehabilitation Research and Development, Vol. 29, No. 1, Published in 1992 on pages 13 through 18, a copy of which will be supplied.
Human gait, the manner of walking and running, is influenced by a number of factors that include foot structure, physical characteristics, muscle action, ground reaction forces, joint kinematics, and the presence of shoes and their structure. Determination and monitoring of human gait is important in athletic activity, medical diagnosis, and normal human motion and movement, particularly since injuries to the lower extremities during walking or running depend on extrinsic factors such as velocity, frequency of walking or running over time, equipment, and terrain. A method for performing this quickly, accurately, and inexpensively would clearly be beneficial. The device described here provides an effective method for measuring and analyzing human gait and identifying human gait style.
Over the past ten years, studies have shown that shoes can significantly contribute to injuries of the lower extremities, especially when shoe structure is not properly matched to foot dynamics. Pronation and supination have been shown to be substantially influenced by the shoe, wherein shoe structure differences affect the amount of eversion and inversion in the rearfoot. Excessive pronation (over-pronation) is associated with too much movement of the rear-foot during the stance phase of gait, and elevated peak plantar pressure is associated with excessive and abnormal loads on the foot. Both of these factors have been associated with injuries of the lower extremities. The device described here measures foot dynamics both barefoot and inside shoes to provide rear-foot motion analysis, plantar pressure analysis, and gait style analysis, which can assist footwear consumers in proper shoe selection.
Although the embodiment of the present invention applies to a device that measures and analyzes human gait and identifies gait style, the device may be used to measure key factors important in athletic training and sports medicine. This device may also find use in other biomedical and pediatric applications such as orthopedic diagnosis and rehabilitation. The device can be used to measure three dimensional foot and shank acceleration, angular velocity, and position, by calculating the tilt of the independent foot and independent shank, the rearfoot motion angles of inversion/eversion, adduction/abduction, dorsiflexion/plantar flexion, stride length, pace, maximum plantar pressure, mean plantar pressure, and center of pressure gait-line.
The invention is a portable gait analyzer comprising of at least one independent rear foot motion collection unit, at least one independent lower shank motion collection unit, plantar pressure collection unit, at least one processing and display unit, and soft casing unit. The invention comprises a plurality of accelerometers, rate sensors, force sensor resistors, and pressure sensor components for the acquisition of acceleration signals, angular velocity signals, foot force signals, and foot pressure signals to be processed. The invention comprises at least one central processing unit, a plurality of memory components, input/output components and ports, telemetry components, calibration components, liquid crystal displays components for the processing and outputting of three dimensional acceleration, angular velocity, tilt, and position. The rearfoot motion collection unit and lower shank motion collection unit interact with the processing and display unit to calculate rear foot kinematic data crucial to identify the motions of pronation and supination. The plantar pressure collection unit interacts with the processing and display unit to calculate plantar pressure data crucial to identify the center of pressure line and excessive and abnormal loads on the sole of the foot. These factors of rear-foot kinematics and plantar pressure lead to gait style identification.
These and other objects and advantages of the present invention will be more readily apparent from the following detailed description of the preferred embodiment of the invention, when read in conjunction with the accompanying drawings.